Liquid fuel feeder for a vaporizing type burner



1957 M. W.YCREW ET AL 2,802,628

LIQUID FUEL FEEDER FOR A VAPORIZING TYPE BURNER Filed Oct. 8. 1951 3 Sheets-Sheet l Maze/5 I14 Ceew W022 s 6. Wag-x5e ATTORNEYS Ailg- 1957 M. w. CREW ET AL 2,802,628 7 LIQUID FUEL. FEEDER FOR A VAPORIZING TYPE BURNER Filed om. s, 1951 s Sheets-Sheet 2 INVENTORS Make: 1% Ceew I l mews 6. I'M/Ease BY L ATTORNEYS.

Aug. 13, 1957 M. w. CREW ET AL 2,802,623

- LIQUID FUEL FEEDER FOR A VAPORIZING TYPE BURNER Filed Oct. 8, 1951 1 3 Sheets-Sheet 5 L 7 me l 0 67 flu. v

I Mme/s 'IL (efw W/zeeE/v 6. MIEELEQ ATTORN E Y5 LIQUID FUEL FEEDER FOR A VAPDRIZING TYPE BURNER Morris W. Crew, Milwaukee, and Warren G. Wheeier, Wauwatosa, Wis.

Application October 8, 1951, Serial No. 250,272

6 Claims. (Cl. 236-73) The invention relates to a liquid fuel feeder for a vaporizing type burner providing metering and pumping apparatus for constant operation during pilot fire, high fire andsubstantially stepless modulation therebetween.

The invention provides, in a unitary device, a feeder directly responsive to a thermostat which controls only the quantitative flow of fuel to the burner by reason of its control in stepless modulation of the output of a positive displacement fuel pump between a minimum volume for pilot operation of the burner and a maximum quantity for high fire, thus removing any necessity for ignition device which would be required during the on and oflE operation of a burner; and also providing for safe operation due to the factthat during pilot operation of the burner no small orifice metering means are necessary and the valve operation incident to pilot consumption of fuel is the same as for high fire and involves repeated valve opening and closing whereby to clear the valves of any debris or other maladjustment.

Furthermore, this invention meets the problem presented in space heaters where a warm air circulating fan may cool a vaporizing type pot burner to an excessive degree during periods of low feed of fuel. This is accomplished by automatically shutting off the circulating fan when the direct connection of the thermostat to the pumping means dictates a predetermined minimum setting of the pump-metering apparatus.

Additional features of this invention include the provision of a special stop to determine a minimum feed of fuel equivalent to pilot flame requirement; also the provision of means to shield a thermal element, in the thermostatic control, from fuel pump pulsations.

In the particular embodiment of the invention shown in this application, fuel is fed from a fuel reservoir located at any practical level, whether above or below the space heater and its burner. One practical limit will be in the neighborhoodof 22 feet for suction of fuel from a reservoir below the space heater. The height of the reservoir above the space heater would be limited to a head which will be practically held by spring loaded valves in the fuel feed system.

Heretofore no practical fuel feed device for vaporizing type pot burners has included practicalprovision for modulation of burner operation where the space heater equipped with the burner has included provision for forced space heating air circulation augmenting the usual gravity feed of warm air through the jackets of the heater. Furthermore, all of the previously devised fuel feeders for such burners and space heaters have been subject to objectionable and dangerous operation due either to the uncertainty of float valve control of the level of fuel or due to the uncertainties and expensive operation of special devices for power feed of the fuel from the reservoir to burner. This invention meets these requirements.

In the drawings:

Fig. 1 is a perspective of a representative type of space nal-of the jacket of the heater, at the rear thereof, pertaining to this invention.

Fig. 2 is a vertical section through the lower portion of a space heater and showing the installation of this new fuel feeder which is shown in elevation.

Fig. 3 is a vertical section on line 33 of Fig. 4 through the fuel feeding control device embodying this invention.

Fig. 4 is a horizontal section on line 4-4 of Fig. 3 and showing the mechanism of the control device in plan.

Fig. 5 is a section on line 5-5 of Fig. 4 and showing the automatic safety shut-down mechanism for stopping flow of oil to the burner in the event of flame failure.

Fig. 6 is a section on line 66 of Fig. 3.

Fig. 7 is an end elevation of the control device showing the relation of the thermostat to the control mechamsm.

Fig. 8 is a detail in horizontal section of the pump and safety float mechanism, the view being taken on line 8-8 of Fig. 6.

Fig. 9 is a view somewhat diagrammatically set forth and showing an alternative form of power drive for the pump control according to this invention.

Fig. 10 shows a wiring diagram for electric features of this control device.

Fig. 11 is a view comparable to Fig. 3 but showing an alternative form of pump arm and thermostatically oper ated stop arm.

,Fig. 12 is a view comparable to Fig. 4 and showing the alternative construction disclosed in Fig. 11.

An important feature of this invention is the provision of a closed fuel feed conduit from fuel reservoir to fuel burner with a control device in the conduit connections comprising pumping apparatus including pump .valves performing all of the functions of positively moving the fuel from reservoir to burner, metering the fuel in quantitative modulation throughout the entire operating range of the burner from pilot flame to full Operaheater, the view showing the relattion of the parts extercapacity.

Usually in the construction of space heaters, there is an exterior shell or jacket 20 which may be of any desired shape but which is spaced from the combustion chamber 21 in which the greater part of the combustion of fuel takes place. Below the combustion chamber 21, the pot burner 22 is of differing shapes and sizes in the various makes of space heaters, but it provides a surface 23 upon which liquid fuel is fed in such quantities as to provide the needed heat and in such quantities and under such conditions of temperature of the surface 23 and the surrounding burner surfaces as to assure that the liquid fuel is vaporized for proper combustion above the surface 23. The shell or jacket 20 of the space heater has louvers 24 in the lower portion thereof for the admission of cool air from the zone outside of the space heater. These louvers are adjacent the floor or lower surface upon which the space heater is supported. Other louvers at 25 and 26 in the upper portion of the jacket of the space heater provide for passage of heated air into the room or space to be heated. As a practical incident of the combustion of the fuel in the chamber 21, a certain portion of the cool air admitted through the louvers 24 passes through openings at 27 and 28 for primary and the floor of the control unit 4%. piston 45 are a number of ports 47 closed by flap valves bustion rising in the chamber 21 pass out a flue connection at 29 as is well understood in the art.

In a large percentage of space heaters, a fan device 3:? suitably electrically motorized as shown'in motor 31 assists the gravity flow of air through the jacket space of the heater, but as will be observed from the relation of the parts thus far described the forced feed of air tends to cool the surface 23, and the operator in control of a space heater equipped with such fan device as that shown at 3631 must use care in the operation since a low rate of fuel feed onto the surface 23 may permit that surface to be cooled during forced feed'of air through the jacket 26 so as to interfere with eflicient vaporization i of fuel. This feature of operation of forced air circulation will be discussed in greater detail below SIIICG, this invention includes provision for automatic energizing and deenergizing of the motor 3i in accord with 'modulated feed of fuel. 7

Passage of fuel to the surface 23 takes place through a standard form of feeder pipe 35 which is usually disposed in' slanting position, as shown clearly in; Fig. 2,

so that the lower margin at the point of conne'ction with the burner provides a spillway or wier for the fuel-passing to the-burner. A trap fitting 36 and trap shaped pipe 37 is connected at the outer lower end of the feeder pipe 35. To the trap 37 the control device forming the principal part of the structural elements of this invention is connected. 7

The. feeder control embodying this invention comprises a control unit 40 mounted upon a bracket 41 in such a position at a low point upon the jacket 20 of the space heater that a pair of chamber elements 42 and 43 forming part of the unit are substantially upon the same level asthe feeder pipe 35. In these chambers 42 and 43, are incorporated the pump unit and safety float unit now to be described in detail with their operating and control mechanism. In a'preliminary way, it may be stated that the pump unit in the chamber 42 pumps fluid fuel to .a suflicient height in the chamber 42 so that it may spill through an opening at 44 into chamber 43 and the fluid fuel may then pass freely through the chamber 43 and into trap 37. In the normal operation of this device, the pump chamber 42, is, of course, full of fuel and the level of fuel in the chamber 43 is that which 'is determined by the level of the spillway at 44 where the feed pipe 35 spills its contents out upon the surface The pumping apparatus in chamber 42 has the simplest plunger type characteristics. The chamber is cylindrical in shape and has a plungeror piston 45 attached to a plunger rod 46 guided through a bearing at 46' in In the bottom of the 47'. These flap valves are preferably made of neoprene coated nylon fabric and they are shaped in any practical manner as for instance shaped as shown in Fig. 8. The

flap valves are biased resiliently to closed position by a disk spring 48 which in turn is held centrally by a retaining ring 49 in a groove in hub 5 forming part of the piston 45. The entrance for fuel passage to the chamber 42 is provided through port 51 in the lower portion of the chamber and passage of fuel through this port is controlled by another flap valve 52 of material similar to the valve material at 47'. Here too a spring 53 secured in position by a screw 54 loads this valve to prevent uncontrolled passage of fuel into the chamber 42.

Thus as plunger 45 is reciprocated in the cylindrical chamber 42, fuel is pumped through supply pipe 55 and when the chamber 42 is filled, the continued operation of the pump causes fuel to spill over through the opening at 44 into chamber 43. a

It will be seen that the entire feed and control directly of the oil or fluid fuel from the reservoir (not shown) through the supply pipe 55, through the pump and the feed pipe 35 to the surface 23 is urged and controlled solely by the piston 45 and the valves of the pump. There are no other valves for metering the fuel; there is no constant level chamber to supply a head which may influence'a metering valve. In other words, the pump and its valves constitute the only metering and supply mechanism. There need be no shut-off valve between the reservoir and the surface 23 other than the effective stoppage of oil by the piston 45 when it ceases to move. i

The motivation, modulation of movement, and thermostatic effect upon modulation of movement of the piston in accord with this invention will now be described. The upper end of the plunger rod -46 is connected to the swingable end 60 of pump arm 61 fulcrurned upon a stub shaft 62. This stub shaft is mounted upon a bracketlike partition element 63 centrally upstanding in the housing of the unit 40. The pump arm is made up of two laterally spaced flanges 64 and 65 and each of these flanges is provided with a V-shaped cam extension 66. On the other side of the partition 63 is mounted a constant speed motor 76 and a gear train, housed in 'a gear Cease 71, the output shaft ofwhich at 72 rotates one revolution per minute and-extends through partition 63. A pump drive plate 75 mounted on shaft 72, and therefore .revoluble at one revolution per'minute is disposed vertically between the spaced portions of the arm 61, and since the plate 75 is provided with six pump drive pins 76 extending at either side of the plate, these pins are ,in position to act upon V-shaped cam extensions 66.

A rigid extension of pump arm 61 extending downwardly at '77 is provided with a thermostat abutment at 78, and a thermostat stop rod 79 is adjustably reciprocable so that its terminal surface is in position to be abutted by the thermostat abutment 78. The other end of the stop rod 79 is secured to one face 80 of a thermostat bellows actuator 81. The bellows is housed in a per- ..forated thermostat housing 82 secured to one of the outer walls of the unit 40, and since the bellows 81 itself is mounted upon the end of rod 79, the bellows floats in this housing 82 except as it is controlled by thermostat set screw 83 which is in threaded relation to the housing 82. A compression spring at 84 between the bellows 81 and a wall of the unit 40 constantly urges the bellows and the stop rod 79 toward the left as seen in Fig. 3.

Bellows 31 is filled with a suitable thermally expansible fluid especially expansively active in the temperature range .where this control is to be used. In other words, especially 'eXpansible between the temperature range between 60 and 80 where the space heater controlled by this device is to be used in a dwelling. A mechanically operable wheel at 85 on the screw 83 is used to adjust the .setting of the rod 79 according to a calibrated dial at 86 as shown in Fig. 7. Thus as the rod 79 is thrust to the right by the expansion of bellows 81, the arm 61 is prevented from descending farther than the end of rod 79 will permit movement of the abutment '78, with the result that V-shaped cam 66 will only be contacted as to its outer portion by pump drive pins 76. Obviously .this shortens the stroke of the plunger 45 and limits and modulates the quantity of fuel pumped by the pump.

It is Well known that space heater pot burners of the vaporizing type consume efficiently a minimum'of approximately two cubic centimeters of fuel oil per minute and maximum quantities of fuel'oil depending upon the size and design of the particular burner if the feeding device satisfactorily and reliably feeds the fuel at this rate. Popular types of burner at tthe present time efli ciently burn up to fifty cubic centimeters per minute. For such burners the pump is designed with a diatreter plunger and the maximum range of movement is one inch to provide 47.8 cubic centimeters of fuel oil feed. The Vshaped cam 66 is therefore designed to move the plunger one inch when the. V-shaped cam and .the arm 61 are permitted by the rod 79 to descend for full ,cam action by a drive pin 76.

in the jacket of the heater.

The switch 99 is normally closedby the weight of.

float 110 as it hangs upon safety rod .111 secured to spring leaf 101 in the switch. However, the spring leaves 101 and 102 carrying the points 100 of the switch 99 are biased to open the points. Thus when for any reason the fuel in chamber 43 accumulates sufliciently to support the weight of float 110 and the safety rod 111, the switch 99 opens and the motor 70 stops.

Reference has already been made to the necessity for stopping the rapid circulation of cool air against the lower portion of the burner 22 when the quantity of fuel being burned is reduced to a small amount; for instance, in V a particular burner suitable for the heating of two rooms, it has been found that any fuel consumption below eight cubic centimeters per minute creates a situation as to the temperature of the surface 23 which is inimical to efficient combustion where forced air circulation prevails In accord with this invention,

a special control device for the fan and motor -31 is included in the unit as follows. p

A fan control arm 115 is mounted on the same stub shaft 62 that carries the pump :arm 61, in fact it finds its bearing upon the stub shaft between spaced flanges 64 and 65 of the arm 61. This fan control arm has an abutment 116 to bear upon the end of stop rod 79 beside the abutment 78 which forms a part of the pump arm 61. Fan control arm is offset as seen most clearly in Fig. 4 and is provided with an adjusting screw 117 to bear against leaf 118 of fan switch 119. This switch is normally closed, but the weight of the arm 115 by the adjusting screw 117 is adjusted so that any position of the stop rod 79 which will cut down the range of movement of pump piston 45 for delivery of less than eight cubic centimeters of fuel oil per minute will raise the fan control arm 115 sufiiciently to permit switch 119 to open. As shown in the wiring diagram, Fig. 10, a Wire 120 constitutes the hot wire to switch 119. When the switch 119 is closed, the wire 121 extending from the switch 119 to the motor 31 energizes the fan motor. and the circuit is completed through ground wire 122.

As to each of the circuits to the motor 70 for operation of the pump or motor 31 for operation of the fan, a .ter-

minal panel at 125 within the unit 40 is used to carry the ground line 122 and the two hot wires 120 and 95.

In Fig. 9 is shown an alternative operating mechanism for the pump. The pump itself as to the pump chamber and plunger 45 is identical with the construction shown in Figs. 3 and 6, but the motor 70 and gear train in a housing are so designed as to rotate shaft 131 the proper number of revolutions per minute for the desired number of strokes per minute for the pump plunger 45. For instance, the operate the plunger at a rate comparable to the operation of the plunger in the device of Fig. 3, the shaft 131 would be rotated six times per minute so as to cause the pump plunger to be reciprocated six times'per minutes just as the six pins in the Fig. 3 construction force the V-shaped cam 66 to operate the plunger six times per minute.

On the shaft 131 is an eccentric earn 132 to bear against the. under side of pump arm 133. Pump arm 133 is L-shaped and has an abutment at 134 to bear against stop rod 79 just as pad 78 abuts that rod in the Fig. 3 construction.

When the stop rod 79 is thrust into position. against I abutment 134, the cam rotates through at least a portion of its orbit released of the load of the arm 133, and of course, when the stop rod is thrust to the right to its extreme position, the pump arm 133 is only permitted to drop slightly from the. extreme uppermost position to which the cam forces it and the stroke of the plunger 45 is shortened to the minimum feed setting determined by the manually set pilot flame control at 85.

Fig. 11 not only shows another alternative operating mechanism for the pump, but also shows means for isolating the thrust incident to pump operation so that such thrust may not influence the thermostat or interfere with its arcuate determination of amplitude of pump operation.

Furthermore, in this alternative construction the easing around the operating mechanism is oil tight in the lower portions thereof and the lower portion is filled with oil so as to immerse some of the operating mechanism and insure lubrication and quiet operation of the moving parts.

In this alternative construction, the casing for the unit 40 is designated at 150. The pump chamber as shown at 151 (Figs. 11 and l2) is provided in the corner of the easing rather than depending therefrom as in the Fig. 3 disclosure. A port 152 in the pump chamber wall passes fluid fuelinto the lower portion of the casing 150 for lubrication and silencing purposes as referred to above and a separate port 153 passes fluid fuel into float chamber 154 for passage to the oil burner. In this instance plunger operating pump arm 155 is fulcrumed at 156 and is provided with a tortion spring 157 to urge the arm to a position which will lower the pump plunger to its lowermost position. The shaded pole motor 158 drives a gear train indicated generally at 159, the output of drive of which is represented by a pump arm drive plate 160. This plate is so driven by the motor and gear train as to revolve at six to ten or any suitable number of revolutions per minute whereby a drive pin 161 extends outwardly from the plate 60 sufiiciently to bear upon a bearing plate 162 forming a part of the pump arm 155 thus providing a drive in which the plate rotating counterclockwise as shown in Fig. 11 will thrust the bearing plate and the extended arm of pump arm 155 downwardly on the upward stroke of the plunger of the pump.

In this alternative construction the means for modulating the extent of plunger movement is provided in a thermostatic stop arm 165 fulcrumed at 166 upon bracket 167 mounted upon the interior of the case 150. This thermostatically operated stop arm has a flange 168 apertured to receive the end 790 of the thermostat stop rod 79 so that upon expansion of the bellows 81 the curved portion of the stop arm is thrust into engagement with the bladed tip 170 of the pump arm 155. It will be noted that the inner curved face 171 of the stop arm 165 is serrated with relatively small serrations so as to provide as nearly as possible for stepless modulation of the stopping effect of the stop arm 165 as it is moved by the thermostat 81. Thus as the thermostat expands in response to rising heat in the space heated by the controlled space heater, the lower portion of the stop arm 165 moves farther to the right as seen in Fig. 11 and the bladed end 170 will engage the stop arm serrations farther and farther down the arc of the stop arm thus preventing the bladed end 170 and the bearing plate 162 from moving in the one direction upwardly toward pin 161, and the amplitude of movement of the pump arm 155 will be lessened as temperature increases. The upper end 172 of stop arm 165 moves in an arc to and from a factory adjusted set screw 1'73 which determines the minimum feed rate of the pump-such minimum feed rate being determined by the lowermost quantitative delivery which would be safe for flame maintenance in the particular burner to be controlled. Furthermore at 174 provision is made for manual threaded adjustment in the event that the user of this particular controlled space heaterdesires a higher minimum. The cone shaped tip of the minimum adjusting member at 174 may be moved into position to adjustably obstruct swinging movement of the upper end 172 of stop arm .165.

It will be noted that the useof a stop arm 165 independently mounted upon its own bracket supported..fulcrum 166.,isolates the thrusts ofthe arm 155 from the thermostatic member 81 thus providing a more accurate operation of the thermostatic modulation of the amplitude of pump operation.

It will be apparent from the above description that .the operation of the fuel feed control device is as follows:

Assuming that the space heater equipped with thiscontrol device is being operated for the first time and is devoid of any fuel oil in anyof thepart s, and assuming that a reservoir tank of fuel oil vis connected to the supply pipe 55, switch 97 -is turned from the off? position to the on position thus completing the circuit' through motor 70. The gear train in the case 71 will rotate shaft 72 and plate 75 one revolution per minute. Six pins 76 bearing upon the under surface of V-shaped cam 66 force pump arm l upwardly six times per minute. As the pins successively pass beyond the point of cam 66, the arm 61 drops by gravity (assisted if necessaryby tortion spring 61-). Each time pump arm 61 rises and faills, the plungerrrod 46 connected to the pump arm 61 raises and lowers Presumably, at the time that the heater is started the.

room to be heated by the space heater is quite cool and the thermostatic bellows 81, located fairly closely to the floor, is in retracted position to which it is thrust by the spring 84. This means that the stop rod 79 is in its retracted position to the-left in Fig. 3 and the abutment pad 7 S does not strike the stop rod 79 until pump arm 61 has dropped to, or almost to, its extreme lowermost position. Thus the pump plunger travels through its greatest, or approximately its'greatest pumping stroke and a relatively large quantity-of fuel is pumped through the port 44 and is passed by gravity to the burner.

The burner is lighted in theusual way by dropping a small quantity of burning paper into the bowl of oil which accumulates upon the surface 23. As combustion is successfully started, the surface 23 rapidly heats and the efficient vaporization and combustion of fuel progresses toconsume the quantity of oil which is being fed.

When the temperature of thespace to'be heated increases, the thermostat bellows 31 is soon influenced especially since the fan 3%} will draw room air to the vicinity of the thermostat and, as determined by the setting of the manual calibrated wheel at 85, the expansion of the contents of the bellows will cause the stop rod 79 to be thrust to the right to shorten the stroke of the pump arm 61 and the plunger 45 as described above. Increasingly the bellows will expand until the pumping rate is reduced to the point where the combustion of fuel keeps up with the heat loss in the space to be heated and a balance is struck with conditions such that the thermostat maintains a relatively static position and the pump continues to meter the proper amount of oil or fuel to hold the temperature in the room at the predetermined desired temperature level.

Obviously when a door is opened or other factors increase or decrease the-heatingrequirements, the-thermo stat 81 will change position sufliciently to increase or decrease the stroke of the pump. If heating requirements are lessenedto the point where substantially no heat is required to-maintain the desired temperature in thespace to be heated, the-thermostatbellows 81. .willexpand to thepoint where the pump. arm 61 is prevented from moving to a greater extent than is .necessaryto maintain a pilot fire in the burner. 22. Thisufpoint is determinedby the stop as abovedescribed... 1

However, ,if the heating requirements, are, lessened and the amount of fuelnburned in the vburner 22, drops below approximately eight cubic centimetersper minute, fan 30 which has been operating at'all times since the switch 97 was closed will cool the surface 23.sufiicie ntly-to adversely affect the efficiencyof-combustion in the burner and the.

predetermined setting-of adjustingscrew 117 will, in this critical point of pump operation for less than eight-cubic centimeters-per minute, automatically open switch 119 for stoppage "of the motor 31 and the .fan,.30.. Thereafter in the continued minimal or pilot light operationof the burn-:

er, the only heat-circulation.through..the ,jacket of f the space heater 20will be bycgravity and if the requirement for heat is lessened to the point of. pumpoperation sub-. stantially to the point of two cubic centimetersper minute,

only an actual pilot fiame will bedeveloped in the burner and the heat output of the space heater will beat a minimum hardly-detectable by persons in the space to be heated.

For a number 'of reasons-well known to those skilled in thisiartyit is a fact that flame failure doesgoccurin the burners ofthese space heaters at times and provisions for shut-down of fuel-feed at times-of fla e failure is a' For this reason the float in safety requirement. chamber 43 and the safetyyswitch 9 'operated by the float is provided. The float l ldis a relatively shallow one and is so designed as to operate upon a change in position of approximately /4; of an; inch. Therefore, when the level of liquid fuel in the chamber-43 rises approximately &- ofaninch above its usual operating level,

the float weighhis removed from the switch 99 and it opens so asto stop motor 70. This of course stops the pump and no;more fuel is fed to'the burner until the level of fuel is lowered either byca manual drainagegoperation or by relighting of the burner. It is well established that a /3 inch eXtraJdepth of fuel in the burner 22 maybe safely lighted and the operator'need not drain the burner.

before reigniting it.

-At all times when the plunger 4.5 is stopped, there are.

two valve mechanisms to prevent full feed of fuel by gravity to the burner. The spring leaves at 48 and 53 are sulficiently strong to prevent gravity feed of fuel through the valves which they control at any reasonable head of fuel which may. be provided in the usual domestic installation.

Of course, when heating requirements increase the amount of fuel fed by reason of a change of position of the stop rod 79 and a greater feed of fuel than eight cubic centimeters, or any other amount for which the device is adjusted, is again instituted, the fan control arm will drop sufiiciently to close switch-11% and forced air circulation through the jacket of the heater will again prevail. Also when it is intended to hold the temperature in the space to be heated at a differenttemperature level than that for which the device has previously been set, the

manual adjustment of the calibrated wheel 85 will change i the setting of the thermostat 8i and the stop rod 79 to provide a different control basis for the operation of the burner.

It will be noted that the mechanism described above, by

reason of the inclusion of a pump to embody the metering pump, approximately 22 feet of suction head is all that can be expected of it, but this is well within the range of normal domestic space heater installations even for second floor dwelling use.

One of the difiiculties heretofore experienced in the control of liquid fuel to be fed to a burner has arisen because of surface tension. This causes a build-up of fuel in portions of the-feed conduit and the fuel feed controlling apparatus, and then when the surface tension is released or broken, a surge of fuel passes to the burner. In the period when the surface tension is causing a build-up of fuel at the one point, the burner itself may be starved, with resultant loss of flame. It has been observed in the operation of the liquid fuel feeder control provided by this invention that the pumping action positively determines the pulsations or surges, and even though there is a quantity of fuel in the float chamber, in the trap, and in the feed pipe leading to the burner, the relatively frequent pulsations of feed of fuel inherent in the pump action prevent a build-up and prevent a hiatus in the feed of 'the fuel to the burner itself. Even at the lowest practical setting for pilot flame operation of the burner in accord with this invention, the pilot light flame is never starved for lack of fuel.

We claim:

1. A feeder for metered feed of fuel to a space heater burner including a burner and a reservoir for fluid fuel and connections to said burner including a pump chamber, a pump plunger in the chamber equipped with an automatic valve in position to block movement of fluid fuel to the burner, a plunger operating mechanism connected to said plunger for constant operation thereof during burner operation, said mechanism including a motorized revoluble drive member having a pin extending therefrom, a pump arm connected to the plunger in position to be acted upon by said pin in the revoluble movement of the drive member, said pump arm being biased to move to one extreme of plunger movement and the pin of the motorized drive member being mounted to move the plunger contrary to said bias, and a thermostatically adjustably responsive member mounted to interfere with the movement of the pump arm in response to its bias.

2. A heater burner, a reservoir for fluid fuel, connections from the reservoir to said burner including a pump chamber and a pump plunger therein equipped with an automatic valve in position to block movement of fluid fuel to the burner, a plunger operating mechanism connected to said plunger for constant operation thereof during burner operation, said mechanism including a motorized revoluble drive member having a pin extending therefrom in position to move in an orbit, a pump arm connected to the plunger for a complete range of plunger movement, said arm being in position to be acted upon by said pin throughout a portion of said orbit in the revoluble movement of the drive member, and a thermostatically responsive member movable progressively throughout a range of movement and provided with an abutment pad movable into position to limit pump arm movement in one direction.

3. For use with a fuel burner having a liquid fuel reservoir and connections between the reservoir and burner for feed of liquid fuel, a reciprocating pump in said connections to block the passage of fluid fuel when said pump is not operating, a motorized drive for said pump to drive the pump at a predetermined number of strokes per minute, said drive having a modulating connection between the motor and the pump including a pump arm, a motorized revoluble member having a portion positioned to abut the pump arm in only a portion 10 of each revolution of said member, and an adjustable modulating member movable into and out of the path of movement of the arm whereby to limit said movement and thereby limit the portion of each revolution of the revoluble member devoted to movement of the arm.

4. A pump mechanism including a pump operating element movable in successive thrusts throughout an operating range of the pump, and a thermally responsive member movable in an operating range to limit the range of movement of the pump operating element, and a stop arm adjustably mounted upon a support independently of the thermally responsive member but positioned for movement between the operating element and the thermally responsive member, the stop arm being shaped to be abutted by the operating element in varying degrees of limitation of said thrusts as said stop arm is moved by the thermally responsive member.

5. A fluid fuel burner and fuel feeder therefor including a burner, a reservoir for fluid fuel and connections for passage of fuel therebetween, a positive displacement pump having power connections for constant motivation, said power connections including a pump arm mounted for oscillation and having a cam surface, a rotary member having a projecting pin in position to contact the cam surface and force pump arm oscillation in one direction during a portion of the rotative movement of the rotary member, and a thermostat having a pad progressively movable in response to change in temperature of atmosphere effected the burner, said pad being variably positioned to hold the arm in differing relation to the pin according to said temperature whereby the cam will cause greater or lesser arm movement.

6. The burner and fuel feeder of claim 5 in which the pad of the thermostat is provided with a ratchet toothed surface and the pump arm is provided with a bladed end engageable alternatively with teeth of said surface for limitation of movement of the pump arm in a direction opposite the direction of arm movement forced by the cam.

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